Internal gear pump



w. R. EAMES, JR., EIAL 2,968,251

INTERNAL GEAR PUMP Jan. 17, 1961 Filed July 15. 1953 5 Sheets-Sheet 1 Fwd IN V EN TORS By EUQEHE S. W \Tcaeea zMQMw/Qj} PGTORNE'H S PKG-Z wanea R. Eemes 3R.

Jan. 17, 1961 w. R. EAMES, JR, m'AL- 2,968,251

Jan.'17, 1961 W. R. EAMES, JR,

E'I'AL Jan. 17, 1961 w. R. EAMES, JR, ElAL 2,968,251

INTERNAL GEAR PUMP Filed July 15. 1953 5 Sheets-Sheet 5 INVENTORS WALTER R. Eames JR.

ATTORREYS INTERNAL GEAR PUMP Walter R. Eames, Jr., Hazel Park, and Eugene S. Witchger, Grosse Pointe, Mich., assignors to Eaton Manufacturing Company, Cleveland, Ohio, a corporation of Ohio Filed July 15, 1953, Ser. No. 368,157

9 Claims. (Cl. 103-126) This invention relates to pumps and more particularly to improvement in structure of pumps of the Gerotor type having intermeshing external and internal rotors.

It has been determined in the provision of an end plate for an intermeshing external and internal rotor type pump, wherein said end plate is operative to control end clearance of the rotor, that unless the end plate is made very thick the pressure acting thereon to maintain the desired end clearance tends to excessively bow said end plate with the result that the effective and efficient operation of the pump is impossible. It is desirable to have the plate deflect slightly towards the rotors in a controlled manner, such that with the pump rotors under pressure operation a more efl'icient operation is obtained. This condition has required modification in structure of the end plate and its cooperative relation to the pump housing to overcome this problem in a simple and economical fashion.

Broadly the invention comprehends the provision of a rotary pump of the type having cooperating external and internal rotors and wherein teeth on the respective rotors mesh with one another and further in the provision of an end clearance control end plate having a controlled area subjected to fluid pressure from the discharge side of the rotors so as to prevent movement of said end plate away from the rotors while at the same time tending to the slight deflection of the plate against the rotors for eifecively maintaining minimum leakage between the suction and discharge sides of the rotors at the ends of the rotors adjacent the end plate. I

Among the principal objects of the invention is the provision of an internal-external rotor intermeshing rotary pump, that;

(a) Embodies structure providing for the effective and efflcient operation;

(b) Incorporates an end plate therein for the eflective end clearance control of therotors lending itself to the minimization of leakage between the suction and dis charge sides of the rotors of the pump;

Utilizes an end plate for rotor end clearance control having high pressure fluid distribution to a selected area thereof so as to cause the end clearance to decrease as pressure is applied to the pump rather than to increase end clearance as with the normal structures; and

(d) Provides for the communication and control of discharge fluid pressure to the outer annular portion of a rotor end clearance control end plate such as to decrease the overall discharge pressure acting on the plate opposite from the axial end abutment of the rotors on said plate.

Other objects and advantages of the invention will appear from the following description taken in connection with the drawings forming a part of the specification; and in which:

Fig. l is a cross-sectional view of an internal-external rotor intermeshingtype pump embodying the invention;

Fig. 2 is a cross-sectional view of the pump of Fig. 1 taken substantially along lines 2--2 thereof;

" nited States Patent 2,968,251 Patented Jan. 17 1 961 Fig. 3 is a cross-sectional view of the pump of Fig. 1 taken substantially along lines 33 thereof;

Fig. 4 is a partly broken away cross-sectional view of the pump of Fig. 1 taken substantially along lines 4-4 thereof;

Fig. 5 is a cross-sectional view of the pump of Fig. 1 taken substantially along lines 5-5 thereof;

Fig. 6 is a cross-sectional view of the pump of Fig. 1 taken substantially along lines 6-6 thereof;

Fig. 7 is a partly broken away cross-sectional view of Fig. 6 taken substantially along lines 7-7 thereof;

Fig. 8 illustrates an O-ring seal of the type incorporated in the pump as shown by Fig. l;

Fig. 9 illustrates a split resilient locating pin of the type incorporated in the pump as disclosed by Figs. 5, 6 and 7.

Fig. 10 is a cross-sectional view of a modified structure of the type of pump of Fig. 1; and

Figs. 11 through 13 are respective front, side, and rear elevation views of the end plate incorporated in the pump illustrated by Fig. 10.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

This internal-external intermeshing rotor pump was devised for the purpose of providing an end clearance control end plate structure wherein the plate in being subjected on its reverse side, from the rotors, to pressure fluid is not bowed tending to bind the rotors or reduce the efliciency of the pump; By communicating the discharge side of the rotors of the pump to a predetermined face area of the end plate limited in area as by sealing means as an O-ring seal, the high pressure fluid used to effect close controlled end clearance between the rotor ends and the end plate is not of a quantity sufficient to excessively bow the plate yet of a suflicient loading capacity to maintain excellent end sealing of the pump radially across the ends thereof. Communication between the discharge side of the rotors and an annular area ofthe end plate radially externally disposed about the central area of the plate is provided through an opening in the plate within which a split resilient pin is arranged for fixedly securing the end plate in non-rotative relation to the pump housing, while permitting axial movement therebetween.

Referring to the drawings for more specific details of the invention 10 represents generally a rotary pump of the type having cooperative internal and external rotors 12 and 14 respectively.

In addition to the rotors, the pump includes a pump 'housing 16, an end plate 18 and a cover plate 20. The pump housing is in the form of a cup having one closed end 22 and an open end 24 having internally thereof, a circular walled pump pocket 26 and a bore 28 eccentric to the pocket with the end plate fitted in the pump pocket adjacent bore 28 in the closed end of housing 16. The end plate is secured to the pump housing by way of a split resilient pin 30, received in a hole 32 extending axially through the plate and a bore 34 in the housing efiective to inhibit rotation between the plate and housing while permitting axial movement therebetween.

A driving or input shaft 36 for the pump coaxial with the axis of bore 28 projects through a central opening 37 in end plate 18 for journalled relation in a sleeve bearing or bushing 38 fitted in bore 28.

An eccentric bushing 40, that is a bushing having its internal and external peripheries eccentric to one another, is fitted in adjusted position in the pump pocket 26 of housing 16.

Internal and external rotors 12 and 14 respectively are arranged centrally of bushing 40 with the outer periphery of the external rotor journalled for rotation on the inner peripheral surface of bushing 40 and with the internal rotor splined by a cylindrical pin 42 to the shaft 36 for rotation therewith.

The internal rotor 12 is shown by Fig. 3 as having six teeth or lobes 44 whereas the external rotor 14 has seven teeth or lobes 46, such that, upon driving rotation of the internal rotor 12, suction and discharge pumping chambers are formed between the rotors through the cooperative meshing engagement of the teeth of the rotors, said pump chambers extending between intakeand discharge ports 48 and 50 respectively formed in end cover plate 20, for the pump. Cover plate 20 having the intake and discharge ports 48 and 50 therein is fixedly secured to the pump housing over the open end 24 thereof with its ported surface 'or face 52 in axial end abutting relation upon one end extremity of bushing 40 and rotors 12 and 14. In so being secured to the housing 16, end coverplate face 52 contacts a face 59 of housing 16 and serves to squash or deform an O-ring 54, in its assembled position in a 'circular recess 56 provided at 'the open end of housing 16 adjacent the pump pocket 26, into frictional and mechanical engagement with circumferential serrations formed on the outer periphery of bushing 40 at one axial extremity thereof. As such the bushing 40 becomes adjustably secured to the housing, the purpose thereof which appears more fully in Patent No. 2,792,788 of Walter R. Earnes, Jr. for Rotor Pump, issued May 21, 1957.

Bushing 40, and rotors 12 and 14 are of such substantially identical axial length that together with the axial length or thickness of end plate 18 they occupy reasonably accurately the axial distance from an inner surface or face 58 of the closed end of housing 16 to the ported surface 52 of cover plate 20 which abuts the end surface of the housing at the open end thereof. As such one axial face extremity of each rotor and the bushing 40 are in parallel and opposed relation with respect to face 52 of cover plate 20, whereas the opposite axial face extremities of the rotors and bushing 40 are in parallel and opposed relation to a flat face 60 on end plate 18. The opposite face 61 of the plate is in parallel and opposed relation with respect to face 58 of the housing.

In its assembled normally axially held position in pump pocket 26, end plate 18 bears against and deforms an O-ring circular gasket 62 seated in an annular, recess 64 provided in face 58 of housing 16 with the axis thereof eccentric to the axis of shaft 36 and bore 28. By so providing the gasket 62 eccentric toth'e shaft 36 it'provide's two distinct and separate areas'or zones on the axial end face 61 of the end plate. The central zone 66 is not subject to'fluid pressure impingement thereon whereas the annular zone 68 disposed radially'outwardlyof the central zone 66 is subjected to the fluid pressure'ii'npingeinent thereon from the discharge side of the rotors of the pump by reason of passage of pressure fluid through the central cavity in pin 30 and thence through the split therein to a location between the face 61 of end plate 18 andfac'e 58 of the housing. By arranging gasket 62 ec'centrically with respect to shaft 36 in a manner such that the larger area portion of outer zone 68 is directly axially opposite the discharge port, the fluid pressure exerted on end plate 18 from the discharge port is opposed by the force of the fluid at discharge pressure exerted on the larger area portion of outer zone 68.

With pressure fluid impingement on zone 68 of race 61 of end plate 18 the plate is operatively axially movable a small amount to provide an eflective end clearance control for the rotors serving to minimize leakage across the rotors between the pumping chambers formed therebetween'at the end extremities of the rotors.

By limiting the area 'orzone of the end plate 18 subjected to the discharge or high pressure side of the pump bowing of the plate is prevented, whichbowing might otherwise etfect materially the effective and efiicient open tiqn ofthe p- 7 A; v

Shallow recesses 70 and 72 formed in end face 60 of end plate 18 opposite from face 61 thereof correspond in size and shape to the intake and discharge ports 48 and 50 provided in cover plate 20.

An end 74 of shaft 36 which is adapted to be coupled to means for driving the pump extends through a bore 76 of the cover plate 20, which bore 76 is coaxial with bore 28 in the housing. A sleeve bearing or bushing 78, fitted in cover plate 20 serves to support a portion of end 74 of shaft 36 for rotation thereon.

An annular seal 80, mounted in a counterbore 82 of end cover plate 20 on the end thereof opposite from face 52 thereof, has rotative sealing engagement upon end 76 of shaft 36 operative to seal the pump along shaft 36 thereof.

Figs. 10 through 13 illustrate an internal-external rotor intermeshing type pump 100, similar in basic respects to the pump of Figs. 1 through 9 and difiering therefrom primarily with regards to a modified form of end plate 102 incorporated therein.

Pump includes basically in addition to end plate 102, a pump housing 104, a cover plate 106, a bushing 108, and internal and external rotors and 112 respectively.

End plate 102 is at variance in structure to end plate 18 of pump 10 in that the intake passage for the pump communicates, with the suction side or chambers between the rotors, through the end plate 102.

With end plate 102, bushing 108, and rotors 110 and 112 assembled in pump pocket 114 of pump 100, provision is had for the discharge porting 116 in the cover plate 106 whereas the intake porting, not shown, is provided in the housing 104. The intake porting of the housing is adapted to communicate with the intake or suction side of the rotors 110 and 112 through an aperture 118 formed in end plate 102.

End plate 102 in addition to aperture 118 is provided on one end face 120 with a circular shallow boss 122 eccentric to the plate and through which the aper' ture 118 extends. As arranged in the pump pocket in assembly with the rotors 110 and 112 and bushing 108, the face 120 of the end plate abuts end surface 124 of the housing internally thereof with an O-ring sealing gasket 126 mounted circularly on the outer periphery of the boss 122. Gasket 126 is of such diameter greater than the axial height of the boss 122, whereby with the end platehaving its end face in abutting relation against end surface 124 of the housing, the gasket effects a seal between the annular outer and central zones or sections of the end face of the end plate.

An input shaft 128 for driving the pump is rotatably mounted in the housing and cover plate and extends through anopening 130 provided through the boss of the end plate centrally of the sealing gasket 126 and is splined to the inner rotor 110 for driving relation therewith.

Whereas one end of aperture 118 has communication with intake portingin the housing upon end face 120 of the end plate, its other end in end face 132 of the end plate communicates directly with the intake or suction side of the rotors. The aperture 118 as noted from Figs. 12 and 13 increases in size from end face 120 to end :face 132 of the end plate such as to provide a desired accurate port in communication with the intake pump chambers of the rotors.

As a means of securing the plate against rotation relative to the housing an aperture 134 is provided therethrough radially outwardly of the boss 122 through which a pin, not shown, is adapted to extend with a portion thereof received in a bore, not shown, in housing boss and together with aperture 134 provides communication between the pressure or discharge side of the rotors and the section of the end plate annularly outwardly of the sealing gasket 126. A shallow port 138 is provided in end face 132 of end plate 118, providing communication between the apertures 134 and 136, and the discharge side of the rotors. The discharge side of the rotors are communicated through appropriate discharge porting in cover plate 106 for delivery therethrough of pressure to apparatus to be actuated by the pump.

With the sealing gasket so arranged on the end plate 118 in sealing array on end surface 124 of the housing and with the discharge and intake sides of the pump communicated respectively to the annular outer and central zones or sections on end face 120 of the end plate, an effective pressure control and clearance operation of the end plate is achieved.

Although the provision for reducing the area of the end clearance control end plate subjected to the discharge side of the pump is herein accomplished by arranging sealing gaskets eccentric to the pump shaft so as to properly accommodate the pump structures disclosed, it is readily conceivable that in pump structures at variance herewith that the sealing gaskets 64 and 126 could be positioned other than as here disclosed and defined. It is thus evident that the invention herein is founded in the provision of a controlled area on the end plate being subjected to the pressure side of the pump, whereby effective end clearance for the pump is achieved without detriment to the end plate or inefficiency in pump operation. The appended claims are couched in terminology to express the inventive concept presented hereby.

What we claim is:

1. In a rotary pump, in combination, a housing having a pump pocket therein and first and second end faces at the axial opposite ends of the pump pocket, a shaft rotatably mounted in said housing in perpendicular relation with respect to said faces, an end plate within said pump pocket in said housing having a central opening therein and to receive said shaft having a first flat end face arranged in parallel and opposed relation to the first face of said housing and a second fiat end face on the end thereof opposite said first end face thereof, a pair of inner and outer rotary pumping elements disposed one Within the other and eccentrically with respect to each other and having a suction side and a discharge side arranged in said pump pocket, axially intermediate the second end face of the housing and the second flat face of the end plate within said pumping chamber, with the opposite end faces of each of said pumping elements arranged in parallel and opposed relation respectively with the second end face of the housing and the second fiat face of said end plate, said second face of the housing being provided with a pair of ports therein one registering with the suction side of said pumping elements and the other registering with the discharge side of said pumping elements, said end plate having an aperture there through providing communication between the discharge side of said pumping elements and a pressure loading chamber intermediate said first flat end face of said plate and said first face of said housing, and an annular sealing means surrounding the axes of said pumping elements and being otfset toward said suction side and disposed in sealing arrangement axially between said first end face of said plate and said first face of the housing intermediate the axis of said plate and the outer periphery thereof so as to provide an outer and inner chamber arrangement of said pressure loading chamber, said aperture being communicable with said discharge chamber and said outer chamber so as to subject a greater portion of said first end face of said plate to the discharge pressure from said pumping means, and said seal so disposed as to circumferentially exclude communication of said outer chamber with said inner chamber whereby said end plate is substantially pressure balanced.

2. In a rotary pump, in combinatioma housing having a cylindrical walled pump chamber therein and first and second end faces at axial opposite ends of said chamber lying in planes perpendicular to the axis of the chamber, a shaft supported for rotation on the housing and extending into the pump chamber with its axis substantially perpendicular to the end faces of the housing, a circular end plate in the pump chamber having a central opening therein to receive said shaft and having its external periphery in bearing engagement with the cylindrical wall of the housing and with at least a portion of a first axial surface of the plate in end abutting engagement with the first end face of the housing, said plate having a second end surface, oppositely disposed from the surface thereof in engagement with the first end face of the housing, lying substantially perpendicular to the axis of the shaft, pumping means, in said chamber, axially intermediate the second end face of the housing and the second end surface of the plate comprising inner and outer rotary pumping elements disposed one within the other eccentrically with respect to each other and pro viding suction and discharge chambers therebetween with one axial end surface of said pumping elements in parallel engagement with the second end face of the housing and with the other axial end surface of said pumping elements in parallel engagement with the second end surface of the plate, means inhibiting rotation between the plate and housing, a pressure chamber disposed between the first axial surface of the plate and the first end face of the housing, and an annular sealing gasket surrounding the axes of said pumping elements and being offset toward said suction chamber and disposed in sealing arrangement in said chamber and establishing separated central and outward annular zones in said chamber and on the first surface of the plate in said chamber, said outward annular zone being substantially axially opposed to said discharge chamber, said plate having an aperture therethrough providing communication between the discharge chamber and said outward annular zone of the first surface of the plate, and said seal so disposed as to prevent communication between said outward annular zone and said central zone, and said shaft radially disposed within said central zone whereby the pressure exerted in said discharge chamber against said end plate is substantially balanced by the pressure exerted in said outward annular zone against said end plate.

3. A rotary pump according to claim 2 wherein the means for inhibiting the rotation of the end plate relation to the housing is a pin extending in engagement between the plate and housing.

4. A rotary pump according to claim 2 wherein the housing is provided with intake and discharge porting, and wherein accurate intake porting is provided in the plate providing communication between the intake porting in the housing and the suction chambers of the pump, through the plate radially inwardly of the annular gasket.

5. A rotary pump according to claim 3 wherein the pin is comprised of a hollow sleeve shaped portion having a longitudinal slot extending the length of said sleeve.

6. A rotary pump according to claim 5 wherein the pin is received in the aperture in the plate.

7. A rotary pump according to claim 4 wherein the discharge porting in the housing communicates with the discharge chambers of the pump through the second end face of the housing and the intake porting in the housing extends through the first end face thereof.

8. A rotary pump according to claim 7 wherein the annular gasket is supported on the first axial surface of the plate.

9. In a rotary pump, in combination, a housing having a pump pocket therein and first and second end faces at the axial opposite ends of the pump pocket, a shaft notatably supported in the housingextending into the pump pocket in substantially perpendicular relation to the end faces of the housing, a plate in the pump pocket of the housing having an aperture therein and having a first end surface arranged substantially adjacent the first end face of the housing providing a chamber therebetween and a second end surface oppositely axially disposed therefrom, said first end surface of said plate having a central zone portion and an outer annular zone portion, sealing means to seal said central zone portion from said outer annular zone portion, and inner and outer rotary pumping elements disposed one within the other and e'ccentrically with respect to each other in the pump pocket and having discharge and suction chambers therebetween, arranged in axial abutting relation between the second end face of the housing and the second end surface of the plate, said sealing means surrounding the axes of said pumping elements and being oifset toward said suction chamber, said outer annular zone of the plate being communicable with the pump pressure in said pressure chamber by said aperture formed through said plate and said central zone portion being sealed from said pump pressures in said pressure chamber whereby said plate is substantially pressure balanced.

References Cited in the file of this patent UNITED STATES PATENTS 1,486,836 Hill Mar. 11, 1924 1,780,109 Berglund Oct. 28, 1930 2,044,873 Beust June 23, 1936 2,312,891 Ferris Mar. 2, 1943 2,612,114 Ernst Sept. 30, 1952 2,641,192 Lindberg June 9, 1953 2,649,740 Murray et a1 Aug. 25, 1953 2,665,641 Lauck Ian. 12, 1954 2,702,509 Garnier Feb. 22, 1955 2,793,595 Lauck May 28, 1957 2,816,510 Jarvis Dec. 17, 1957 2,824,522 Compton Feb. 25, 1958 FOREIGN PATENTS 151,361 Australia May 11, 1953 659,600 Great Britain Oct. 24, 1951 

